Piper is being overprotective of her babies, and Leo is on the rampage, determined to vanquish the demon that killed adult Chris, and suspicious of everyone. Paige discovers the Magic School is being closed down, and determines to save it. While possessed by the spirit of Krishna, Leo is tricked into killing an innocent Elder. There is a hint that a bit evil is on the loose.
Paige is arguing for the continuance of Magic School to unsympathetic Elders, when one of the pupils accidentally conjures Lady Godiva. He also brings along a demon who feeds on repression, who starts gaining strength from his surroundings. The sisters manage to send Lady Godiva and the demon back, but have changed history, since he became strong enough to kill her. Now the whole world is repressed and grey, and the sisters end up in jail awaiting a flogging for speaking in the street. They bring Godiva and the demon back, and kill the demon by getting him to overdose on Leo's repressed anger, then get the original pupil to send her home again, restoring everything. The Elders tell Paige the Magic School can remain open, as long as she runs it.
Piper is trying to live without magic, but it's not working. A demon is attacking Wyatt, Wyatt keeps orbing Chris away, and her sisters want a Wiccaning ceremony for Chris. Leo hunts the demon, while Grams tries to cast an anti sibling rivalry spell. it works on the boys, but backlashes on the sisters, who become truculent teenagers. Eventually Leo discovers the the demon is himself, conjured from Wyatt's bad dreams. The demon is banished, the sibling rivalry spell is undone, and the Wiccaning goes ahead.
An ancient cursed pirate needs the Charmed Ones to steal a golden chalice for the Fountain of Youth. Their quest is hindered by Inspector Shepard, but aided by FBI agent Kyle Brody, who seems to know all about them. Leslie fakes a competition to win a date with Phoebe, but she stands him up because of the pirates.
Paige puts a protection spell on an innocent to protect him from a half-demon killing all his relatives to rid himself of his human soul. But the spell misfires, and keeps him alive when he should be dead. The Angel of Death discovers this means no-one else can die, so he conspires with the demon to kill the man. Even then, there is a huge backlog of souls to collect, so Death temporarily kills Piper to aid him in the process. When Piper discovers the next soul on her list is Phoebe, the sisters come up with a plan, but that ends up with Paige getting killed instead. Eventually they swap the half-demon's for Paige's, and all return to life. Agent Brody sees Piper reawake in the morgue.
It's a rare blue moon, and the sisters are feeling cranky. The Elders decide to replace Leo with a new White Lighter. When the new guy is found savaged by monsters, suspicion falls on Leo. A plan is set up to prove Leo's innocence by making sure he has an alibi the next time, and planning to capture the monsters. But the monsters are actually the sisters, being affected by the moon. Then the floating faces get a demon to posses Leo and attack the Elders. Leo is finally exonerated, but he decides it's too dangerous to stay with Piper. Agent Brody knows something of the coming danger, and wants to help.
Agent Brody has discovered people who miraculously escape a fire, only to die almost immediately. He enlists the sisters' help. Paige discovers that a demon is stealing the victims' guardian angels, who wants them to protect him against the coming evil -- and he steals hers, too. Meanwhile Piper and Phoebe send Leo on a Spirit Quest, where he encounters Chris, who teaches him about love. He is almost healed, when the masked tormenters, the Avatars, plunge him into a new dream, about the destruction that will result from the permanent war between good and evil. Meanwhile the demon has attack Piper and Phoebe -- they manage to vanquish him, but are both killed in the process. Leo agrees to willingly become an Avatar to save them.
A gnome teacher is found shot dead in magic school. Paige calls on Agent Brody for help, and they both get sucked into the black and white 1930's detective novel he was reading. There they discover they have to find the Burmese Falcon before they are killed. Leo, with Avatar help, "defuses the book, allowing Piper and Phoebe to help rescue Paige, by writing in clues and plot devices.
Daryl comes to Phoebe because he thinks Brody is responsible for Shepard's disappearance. The sisters are trying to stop a group of demons killing innocents, but Piper is distracted by whatever Leo is hiding from her. He convinces the Avatars to let him tell her he is now one. He explains the Avatars want to end the battle between good and evil. Piper gradually comes round to the idea, but her sisters are appalled, and go to Agent Brody. He brings a potion that can kill Avatars, saying that they killed his parents. The sisters say they won't let him kill Leo, so he knocks out Paige, and holds Phoebe hostage. He threatens to kill her unless Leo calls an Avatar to be killed. In the struggle, Leo kills Brody, the flask breaks, and the potion starts to kill Leo. The other Avatars arrive, and get Leo to turn back time, to before he told Piper.
The Avatars tell Leo to save the Seer from demons. The sisters are not happy with a demon in the house, but she gives Phoebe a vision of a utopian future without demons, courtesy of the Avatars. She says she will betray all the demons, in exchange for the Elders making her human. The demons release Zankou, a major demon, to kill the Seer. Meanwhile Phoebe discovers that Sheridan is in a coma, due to Kyle. Despite this, Paige moves in with Kyle. Leo tells Piper and Phoebe he is an Avatar, and, swayed by Phoebe's visions, they agree to listen.
Paige tells Kyle the Leo is an Avatar, so Kyle tries to kill Leo with the potion. The Avatars freeze time, and take the potion. The sisters convince Kyle he needs to go back in time to see how his parents really died. Piper and Phoebe prepare to exchange powers, so that Piper can experience the vision of the utopian future. But the demon attacks during the spell, and the powers escape into two innocents, who start using them. In the past, Paige and Kyle witness demons killing Kyle's parents, and accidentally destroying the potion they were trying to steal. Young Kyle finds the supposedly last vial, but grownup Kyle spots a second one... Phoebe convinces the innocents to return their powers by showing them the utopian vision.
The Avatars move their programme ahead, putting all the humans except the sisters to sleep for two hours while they are "changed". The sisters go out killing any remaining demons. However, Zankou has protected Kyle from sleep, and convinced him to kill an Avatar. Kyle uses a paranoia spell to trick Paige into summoning Beta, and kills her with the potion, but she kills him before she dies. Paige is distraught, and the Avatars are weakened. So they put the sisters to sleep too, and when they awaken with the rest of humanity, everyone is just sweetness and light about what has happened, even Paige. All this worries Leo...
As the sisters continue in Stepford mode, Leo begins to realise things are very wrong. Then he discovers that the Avatars are keeping utopia intact by killing those who cause dissent, and changing the rest not to mind. He teams up with the demon Zankou to force the sisters to feel their pain, by making the Avatars kill him. So the sisters rebel, and the Avatars realise that the world is not yet ready for them. They agree to rewind time to just before the change occurs. Leo is returned. Kyle is still dead, but is now a White Lighter. Leo warns Piper that the Elders will not be happy with him...
Paige is looking for a new teacher for Magic School. Drake, a reformed demon [Billy Zane], spelled to become human, turns up for the job. But a sorcerer is after his demon killing powers, in order to attack Zankou. The sorcerer's spell goes wrong, leaving Drake thinking he is Robin Hood. Meanwhile, Kyle has awakened Sheridan from her coma, and removed her memory, but there is always to chance it might be triggered by an interaction with the Halliwells. Which may well happen when she goes after Robin Hood terrorising a telephone company executive. Phoebe manages to save the executive and the sisters vanquish the sorcerer. Drake gets the job, but tells Phoebe he has only a few weeks left until the spell runs out, when he will die.
Darryl asks for help -- his old mentor is possessed. It is the ghost of a man killed in an 1899 nightclub fire, crying out for release. The sisters discover that all the people killed in the fire there are trapped in a time loop, because one of them made a pact with a demon, and doesn't want to die. Phoebe and Drake go into the loop to free them all, but Drake is taken over by the bad guy, and Phoebe is trapped in the fire. Paige and Piper exorcise Drake, and free Phoebe -- allowing all the spirits to be released.
The Elders wipe Leo's memory and powers, and make him mortal. He must now discover whether he finds his way back to Piper, or back to the Elders. Piper is injured by a thorn-spitting demon, and falls into a coma. In limbo, she discovers Cole, who is trying to ensure Phoebe doesn't give up on love. He persuades her to die, so that will send a call to Leo. It, works, and Wyatt restores her to life. Drake dies, and we discover Cole had sent him to Phoebe.
Leo is finding tough to adjust to being a powerless mortal. Zankou sends a demon to attack him, as part of a plan to lure the sisters out of the house so that he can gain control of the nexus. But Wyatt is worried, and shrinks Piper and Leo down to a few inches and locks them in the toy house for safety. Phoebe and Paige go after the demons. Eventually Zankou realises he need the sisters to release the Shadow from the Nexus -- but it can't choose between good and evil, so takes over the neutral Leo, who uses it to get rid of Zankou. In the end, Leo takes over running Magic School.
The demon Katya kills the Guardian of Pandora's Box. But before she can steal it, it moves on to its next Guardian, a student called Hope, who opens it, letting some sorrows out. The demon tricks Piper and Phoebe into leading her to Hope. She forces Hope to open the box fully, letting out all the sorrows. Meanwhile, Paige is coming into her White Lighter powers, but doesn't want them. An Elder persuades her to at least go on a mission to save a future White Lighter, and she finds herself stuck in a lift with a disparate group. Back at the box, Piper and Phoebe vanquish the demon, and persuade Hope that she can recapture the sorrows. Paige learns that the White Lighter she saved was ... herself.
A demon does a soul swap with Phoebe, so that she can kill upper level demons and get herself noticed by Zankou. Paige is given her first charge: a witch who doesn't want to acknowledge his powers. Piper is distracted enough that she doesn't notice the change in Phoebe's behaviour. The demon tricks the sisters into killing her old body, and hence Phoebe. They have to do the soul swap again quickly, to rescue Phoebe before she moves on.
An invisible demon is trying to turn Wyatt evil. In an attempt to communicate with Wyatt, a spell goes wrong, conjuring future-Wyatt back in time. When the demon does succeed, future-Wyatt turns evil. The sisters must vanquish the demon without hurting future-Wyatt, whilst removing the curse on the younger one.
Zankou is on the warpath, shaking the sisters' faith in themselves by killing people close to them: one of Phoebe's classmates, Rose's current charge. And he uses an Alchemist to reanimate the dead, forcing Piper to blast their corpses. All this allows him to steal the Book of Shadows. Meanwhile, Sheridan is also on the sisters' trail...
Sheridan calls Homeland Security down on the sisters. Meanwhile Zankou has control of the Book of Shadows, and the Manor, planning to absorb the power of the Nexus. But first, he is stealing the sisters' powers, one by one. The sisters realise that they may have to sacrifice all to stop Zankou. Fortunately, they remember Pru's ability to astral project, and use that to recover the book, and find the spell to destroy the nexus and Zankou with it, in a big explosion in the Manor. They then adopt disguises, and so everyone, police and demons alike, thinks they died in the explosion, allowing them to live happily ever after...